Re: [8.1.7] Anyone using the DBMS_OBFUSCATION_TOOLKIT.MD5 function ?

From: Thomas Kyte <tkyte_at_us.oracle.com>
Date: 19 Nov 2001 06:22:29 -0800
Message-ID: <9tb4j501gob@drn.newsguy.com>

In article <9tb1sd$1cje6$1_at_ID-18487.news.dfncis.de>, davide_at_yahoo.com says...
>
>
>I have to use the DBMS_OBFUSCATION_TOOLKIT.MD5 function to crypt a
>password that I receive from another system, there are some problems
>thought. The first one is that the MD5 family of functions aren't
>described in the documentation, the second (much more important) is
>that anytime I try to use it, it complains that the function to use
>is not clear.
>
>This is my "bridge" function :
>
>create or replace function crypt(instring varchar2)
>return varchar2 as
> tmpstring varchar2(32);
>begin
> tmpstring := substr(instring,1,32);
> tmpstring := dbms_obfuscation_toolkit.md5(tmpstring);
> return substr(rawtohex(tmpstring),1,32);
>
>end crypt;
>
>trying to compile this function I obtain:
>
>SQL> show err;
>Errors for FUNCTION CRYPT:
>
>LINE/COL ERROR
>-------- -----------------------------------------------------------------
>6/2 PL/SQL: Statement ignored
>6/15 PLS-00307: too many declarations of 'MD5' match this call
>SQL>
>
>Anyone have some hints ?
>
>Davide
>

since they overloaded (unfortunately) the MD5 routine on RAW and VARCHAR2 types -- we need to use the parameter name to distiguish between the two.

Couple of comments

o I wouldn't call it "crypt", its a digest. crypt implies decrypt and its not decryptable. its a one way digest

o i wouldn't substr the input string - you'll want to use the entire string. You'll want to send in the user/password together so that different people using the SAME password get different digests. You might even through a "magic salt" in there (extra string).

o you do not need to substr the return result. The digest is always a varchar2(16)

Here is an example:

ops$tkyte_at_ORA817DEV.US.ORACLE.COM> create or replace function DIGEST( p_string in varchar2 ) return varchar2
  2 as
  3 begin
  4 return dbms_obfuscation_toolkit.md5( input_string => p_string );   5 end;
  6 /

Function created.

ops$tkyte_at_ORA817DEV.US.ORACLE.COM> column digest format a16
ops$tkyte_at_ORA817DEV.US.ORACLE.COM> 
ops$tkyte_at_ORA817DEV.US.ORACLE.COM> select 'TIGER', digest( 'SCOTT/TIGER' )

digest from dual;

'TIGE DIGEST

----- ----------------

TIGER ??U???-?e?_FuS

1 row selected.

ops$tkyte_at_ORA817DEV.US.ORACLE.COM> select 'TIGER', digest( 'TKYTE/TIGER' ) digest from dual;

'TIGE DIGEST

----- ----------------

TIGER Eepj?u?e a^Qq?

1 row selected.

--
Thomas Kyte (tkyte@us.oracle.com)             http://asktom.oracle.com/ 
Expert one on one Oracle, programming techniques and solutions for Oracle.
http://www.amazon.com/exec/obidos/ASIN/1861004826/  
Opinions are mine and do not necessarily reflect those of Oracle Corp 

Received on Mon Nov 19 2001 - 08:22:29 CST